The present invention relates generally to biological sample analyzers and more specifically to a semi-automated analyzer and subsystems thereof capable of simultaneously carrying out a panel of assays on each of a plurality of different biological samples. In one aspect, the analyzer of the invention is adapted to simultaneously assay each of a plurality of biological fluid samples for human IgE class antibodies specific to a preselected panel of allergens.
A significant portion of the population has some allergic reaction to substances such as pollen, animal dander, or other commonly present allergic substances. A key element in the treatment of such allergic symptoms is identification of the particular substance to which a person may be allergic. Previous methods for determining allergic hypersensitivity were performed using direct skin tests on the patient. In these direct skin tests minute quantities of various allergens were injected into or under the patient's skin and the particular patch of skin was subsequently examined to determine whether or not a person had an allergic reaction to the previously introduced allergen.
In addition to being uncomfortable for the patient, patients on certain medications (i.e. antihistamines) cannot be accurately tested by direct skin tests.
Accordingly, a number of in-vitro testing procedures have been developed. Such procedures detect circulating IgE in serum or plasma or other microbiological interactions using an insoluble solid carrier coated with a known quantity of antigen extract derived from a known allergenic substance. The coated carrier is typically exposed to, and incubated in, a sample of the patient's blood serum. If the patient carriers the IgE class antibody which is specific to the particular allergen and which is the cause of the patient's allergic reaction to the allergen, a measurable binding reaction occurs on the carrier during the incubation period. The concentration of the IgE antibody in the sample and accordingly the degree of allergic sensitivity of the patient is then determined by measuring the magnitude of the binding reaction either visually, photometrically, fluorometrically, radiologically, enzymatically, or by other known techniques.
While such in-vitro procedures provide advantages over in-vivo testing procedures, they are not without disadvantages. First, a relatively large quantity of blood is required to test the patient's sensitivity to a large number of specific allergens. Second, testing for a large number of different allergens in separate cuvettes is tedious and time consuming for the physician or technician performing the test.
To this end, efforts have been devoted to develop a system which simultaneously tests for a number of specific allergens utilizing a single sample of the patient's blood serum. For example, U.S. Pat. Nos. 3,941,876 (Marinkovich) and 4,031,197 (Marinkovich) disclose techniques for the screening of different IgE class antibodies. The techniques taught by Marinkovich involve coating an elongated cellulosic body, such as a strip of paper, with separate identified allergens to form bands or islands, which are separated from one another by allergen-free areas. The coated cellulose material is then contacted with a test serum so that serum IgE class antibodies specific for coated allergens will bind to the appropriate bands or islands. The cellulosic body is then washed and subsequently incubated with labelled antibodies that are reactive with the attached IgE class antibodies. The bands or islands are then analyzed for the presence of the labeled antibodies.
U.S. Pat. No. 4,459,360 (Marinkovich) also discloses a similar multiple-component binding assay system which includes a plurality of coated filaments mounted on a support for simultaneously screening a liquid test sample for a plurality of component. Each of the filaments, which are preferably cotton threads, is used to bind a different allergen.
Another example of presently available in-vitro devices is given in U.S. Pat. No. 4,567,149 (Sell et al.), which discloses an apparatus including a well which contains a plurality of elongated strips. Each strip is coated with a separate assay binding component such as an antigen or allergen. The well is adapted to contain a liquid specimen for incubation with the strips. After the incubation process the liquid specimen is removed and the binding reaction which occurred on each strip is determined by known methods.
Still a further device which may be used for effecting a plurality of antibody-antigen reactions simultaneously in one operations is disclosed in European Patent Application No. 0 063 810 A1 (Gordon et al.). The Gordon reference teaches a device for carrying out immunoassays. The device comprises a solid porous support, preferably made of a nitrocellulose material, having antigens and/or immunoglobulins bound thereon by direct application of the antigens and/or immunoglobulins to the nitrocellulose material, thereby forming an array of test areas. The array thus formed comprises a plurality of dots or lines of the antigen and/or immunoglobulins.
Various systems are available which may be used in conjunction with the above-described multiple component binding assay systems to quantify the reactions which occur on the carriers. For example, U.S. Pat. No. 4,558,013 (Marinkovich et al.) discloses an apparatus (which may be used in conjunction with a device such as the one taught by Sell et al.) in which a carrier with an uncoated reference is used to manually produce a strip of photographic film having a linear array of spots or stripes. Each spot or strip on the film has an optical density of indicating the magnitude of the binding reaction on a particular test strip or thread. A scanning densitometer is then used to successively measure the optical density of each film strip, thereby providing a quantitative measure of a patient's reaction to the various allergens.
Another device which may be used with the above-described multiple component binding assay systems to quantify the reaction of each specific allergen is taught in U.S. Pat. No. 4,510,393 9 (Sells et al.) which discloses a portable photo chamber which is used to manually photographically record the magnitude of a chemical reaction evidenced by the emission of radioactivity by a substrate labelled with a radioactive tracer.
Although these methods provide advantages over previously available in-vitro methods, and over the in-vivo methods, they are not without limitations. One major limitation is the fact that the methods for effecting and measuring the reactions on the above-described multiple test spot devices require an extensive amount of manual manipulation by the physician or technician performing the test, which increases the time, cost, and risk of error associated with such tests. For example, known in-vitro procedures require that the multi-component biological test carriers be manually contacted with the liquid sample being analyzed, removed from the liquid sample, washed, and then incubated with a solution typically containing a labeled second antibody that is reactive with human IgE class antibodies. Subsequently, the carrier must be manually removed from the solution and the magnitude of the resulting binding reaction on the solid phase be then determined by autoradiographical analysis in conjunction with the densitometric analysis as proposed by Marinkovich, by fluorometry, or by other known techniques.
In addition, the washing step identified above normally comprises a multi-step procedure including removing waste fluid (for example used or sample solution), adding wash solution, agitating the wash solution for a predetermined time period, removing used wash solution, adding more wash solution, and repeating the cycle two or more times before adding the next reagent. If a number of patient samples are to be analyzed simultaneously, the hands-on time requirements are further magnified. For instance, if ten patient samples were to be analyzed, each washing step alone could involve performing 90 washes. This would probably require a minimum of approximately 30 minutes hands-on time for the technician or physician for each washing step required.
A number of analyzers for automatically analyzing a plurality of biological samples are known. Such analyzers typically include automated apparatus for providing wash, reagent, and sample fluids, and automated apparatus for measuring the results of the test on the samples. See, for example, U.S. Pat. Nos. 4,427,294 (Nardo); 4,451,433 (Yamashita, et al.); 4,406,547 (Aihara); 4,634,575 (Kawakami, et al.); 3,964,867 (Berry); and 4,061,469 (DuBose).
Although these analyzers generally automate the analysis of a plurality of biological samples for the presence of a particular substance, none are suitable for carrying out the procedures required to simultaneously analyze a plurality of patient samples in a plurality of test cartridges each containing a plurality of different test sites and each adapted to simultaneously perform a complete panel of tests on a single sample.
Available systems have still further limitations. For instance, the accuracy of test results derived from devices such as those disclosed by Gordon et al. may be less than optimal. Since the test dots in the Gordon et al. device are formed by contact of the specific allergen with the nitrocellulose without an effective means for confining or isolating the allergen to a specific area, the accuracy and reliability of the results achieved with this device are affected. Specifically, if the dots are arranged in close proximity to each other there is a possibility that an allergen from one test dot will migrate onto a neighboring test dot when the allergen is applied to the support. This migration adversely affects the accuracy of the determination of the patient's reaction to the allergen associated with the neighboring test dot. Second, since the specific allergens are not confined to a predetermined area, the concentration of allergen will vary from dot to dot on each carrier and from carrier to carrier. As a result, depending on the detection technique employed, dot to dot variations in optical density or in the intensity of optical or other radiation resulting from the binding reactions on a dot will occur in dependence on the area over which the allergen initially dispersed during the initial contact with the support. Such variations have a substantial adverse affect on the uniformity and repeatability of test results.
Therefore, in view of the above, it is a general object of the present invention to provide a biological sample analyzer which may be used to automatically and simultaneously carry out a panel of tests on each of a plurality of patient samples.
It is a more specific object of the present invention to provide reaction cartridge means which are adapted for use in such an analyzer to simultaneously test a patent sample for a plurality of different components with a single addition of patent sample and selected reagents and which provides test results accessible by an optical reader directly on the reaction cartridge.
It is also a more specific object of the present invention to provide reaction cartridge conveying means for such an analyzer including means to accurately and uniformly position a plurality of such cartridges in three separate dimensions so that an optical reader can accurately and uniformly read the results of a plurality of tests on each of a plurality of patent samples.
It is also a more specific object of the present invention to provide means adapted for use with such an analyzer to provide access to a large volume of predetermined assay calibration data, such means preferably including reaction cartridge means provided with code means to access corresponding assay calibration data in a data storage means.